Oxygen Sensor: Description and Operation

Heated Oxygen Sensor 1 (Front)







COMPONENT DESCRIPTION
The heated oxygen sensor 1 (front) is placed into the exhaust manifold. It detects the amount of oxygen in the exhaust gas compared to the outside air. The heated oxygen sensor 1 (front) has a closed-end tube made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions. The heated oxygen sensor 1 (front) signal is sent to the PCM. The PCM adjusts the injection pulse duration to achieve the ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical change from 1 V to 0 V.

Heated Oxygen Sensor 1 Heater (Front)




SYSTEM DESCRIPTION
The PCM performs ON/OFF control of the heated oxygen sensor 1 heater (front) corresponding to the engine operating condition.

Heated Oxygen Sensor 2 (Rear)




COMPONENT DESCRIPTION
The heated oxygen sensor 2 (rear), after three way catalyst, monitors the oxygen level in the exhaust gas.

Even if switching characteristics of the heated oxygen sensor 1 (front) are shifted, the air fuel ratio is controlled to stoichiometric, by the signal from the rear heated oxygen sensor.

This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1 V in richer conditions to 0 V in leaner conditions.

Under normal conditions the heated oxygen sensor 2 (rear) is not used for engine control operation.

Heated Oxygen Sensor 2 Heater (Rear)




SYSTEM DESCRIPTION
The PCM performs ON/OFF control of the heated oxygen sensor 2 heater (rear) corresponding to the engine speed.